Posted
by
Soulskill
on Wednesday August 22, 2012 @12:05AM
from the bumpercars:-the-next-generation dept.

Zothecula writes "Videos released by California-based tech research company Aerofex appear to show successful test flights of a prototype hover bike that gains lift from two large ducted rotors. Aeroflex claims its hover bike allows the pilot intuitive control over pitch, roll and yaw without need of artificial intelligence, flight software or electronics of any kind."

The article claims they flew it at 15 ft, and that they think they can way higher like 10,000 ft: if true that's definitely not just ground effect, but unfortunately video doesn't even show the 15 ft trials, only hovering really close to the ground. I would expect them to show off their top tests too.

The think I'm mostly wondering about is stability. How do they do that? Hovercrafts are notorious for their instability, especially smaller craft. Flying them is a tough balancing act.

At least the videos look genuine to me, so it seems to be a real product. Oh well, time will tell how true it all is.

I'm reasonably impressed just by what I saw in the video. That level of directional control is impressive for a hovercraft. From what I've seen you normally wouldn't be able to keep one in your lane on the road which is one of the primary reasons you don't seem them used for consumer travel.

If it can get substantial height that is a real bonus but it is cool stuff either way.

Keep that Star War'sy speeder-bike thingy away from my new car's paint job! I can see pebbles and dust flying around everywhere this thing goes. For stability's sake, throwing a couple of gyroscopes on wouldn't hurt either. As proof of concept, looks promising. I'd still wear a helmet, for now.

Article suggests it was done with a driver on board, though it's not mentioned explicitly. They claim they have not tried to push it to max. height and speed yet (for safety reasons indeed). Though a fall off such a thing at 5m high and going some 50 km/hr will hurt. A lot.

The think I'm mostly wondering about is stability. How do they do that? Hovercrafts are notorious for their instability, especially smaller craft. Flying them is a tough balancing act.

My impression is that it doesn't have good stability. Stability refers to the tendency of an aircraft to correct deviations in its flight path. An aircraft has inherent stability in three axes- pitch, yaw, and roll. Pitch refers to the nose pitching up and down, yaw refers to the nose yawing left and right, and roll is rolling about the long axis. So if a gust of wind rolls one wing up, the plane will automatically compensate and level out-without any action on the part of the pilot. This machine seems to perhaps have decent pitch and yaw stability, but roll stability seems to be pretty minimal. You can watch the machine slowly rolling in the movie; it's presumably the result of having a high center of gravity, like a man standing in a canoe.

As far as I can tell, the machine isn't actually stable, instead the pilot continually makes small adjustments to keep the machine flying level. According to the article, "Aerofex's new proof-of-concept craft keeps itself stable by responding to a human rider's natural sense of balance" and "The company has apparently rectified the issue with the addition of knee-level "control bars" on either side of the vehicle that make the vehicle more responsive to the pilot's movements." So from the video and the article it would seem that they haven't made the machine stable, they've made it controllable, and given the pilot the ability to continually make small adjustments to keep it level. If he gets distracted, of course...

With a bike, you control balance directly -- i.e. leaning and whatnot actually dominates the force on the bike, allowing you to control it with the same reflexes that allow you to stand up and run away from tigers.

What they have with this thing is controls. You're once removed from the action -- your reflexes create inputs that the device acts on. It's a second-order effect, and that means it is much, much more difficult to do without concentration.

There was an Aussie or Kiwi guy working on something similar that had a better layout - it was like a motorcycle with the ducted fans at seat level. This should be more stable than standing completely above the fans.

The article claims they flew it at 15 ft, and that they think they can way higher like 10,000 ft

I'd like to see the calculations they used to arrive at this figure. There's a 25% engine power loss when operating at that altitude. Considering there's also propeller efficiency losses due to lower air density, I highly doubt they have the power to do so.

"but the power:weight ratio and range just wasn't there with 50s engine technology"

Yep, modern batteries should give the required energy storage capacity while electric motors give much better power/torque at very very low weight. Plus the lightweight materials to build the chassis which just didn't exist before the space race and have only improved since then.

In the 50s I imagine the batteries meant an electric motor was just impossible without tethering you to the mains, so it required a internal combusti

The Tesla Roadster is based on the Lotus Elise chassis. The Elise has 217bhp and weighs 914kg, which is 241 bhp/ton. The Tesla Roadster has 248bhp and weighs 1283kg, so 196 bhp/ton. And guess which has a better range?

Personally I'd love an electric vehicle for commuting and short trips, but what you said doesn't really make sense.

Wow, what an incredibly dumb comment. Look at the article title: "Hover Bike". Go look up the definition of "hover", as in "hovercraft". They don't need to fly above ground effect, that's the whole point of a hovercraft, is to stay close to the ground but hover enough that you can fly over rough (roadless) terrain and water.

Unlike most hovercraft this looks like it has decent control. A normal hovercraft couldn't be kept from floating into oncoming traffic on the road. This looks like it could. Beyond rough terrain that has significant benefits in reducing wear on the road and eliminating tires and the hassles that come with them.

First the guys are Engineers, basically math geeks so there cinematography skills isn't so hot. Stability seems pretty good for a proof-of-concept even with an engineer in the driver's seat, I've seen Apache pilots flying a lot more squirrely with the stick of a Kiowa in their hands instead. Strap that thing to the ass of a real rotary wing pilot or even a hardcore motorcycle freak and you'll see a big difference, hell just dropping the center of gravity below the pilots pelvis and the ducted fans above it

Yeah, Drop the CG on the thing and it'll be more stable, also a ultralight helo... as-is, yeah right, when's that last time you've seem a rotary wing fly upside down using a manual control system. Not a proof of concept.

It's pretty obvious that this "thing" doesn't work and they're just looking to stir up a round of suckers, I mean investors. This is almost as bad as the aussi guy who built one and chained it to the ground at 3 points to keep it from flipping.

It wouldn't registered as drive-thru have weight sensors to tell the person when a car approaches. I've tried going through on rollerblades, but it wouldn't trigger the weight requirement. (Didn't want to go inside of out safety concerns.)

Something like that is actually used in hybrid vehicles to regenerate the battery. it's called Regenerative Braking. Using it like you suggest would be like driving with the handbrake on. Also remember that recapturing energy like this is very inefficient, therefore you are better off generating electricity directly from the engine.

I wish I could throw money at a project like this so I could show you mine.:P

If I could, though, I suppose it'd be a scaled-up quadrotor (possibly turbine-powered) with a pilot under it. It seems just more sensible than this two-rotor thing that seems to want to kill its pilot at the slightest provocation.

Also, the fact that it flies without electronics is not a good thing. Multirotor setups, especially those with a high center of gravity, benefit immensely from computer-controlled stability.

Also, the fact that it flies without electronics is not a good thing. Multirotor setups, especially those with a high center of gravity, benefit immensely from computer-controlled stability.

No true, remember the KISS principal. Given that their intended use is in outback and 3rd world places where replacement electronics are likely to be unavailable but a welder is, the more simplistic and basic mechanical they can make it the more durable, usable, and practical it is for their intended use.

It seems to do pretty well, seems easy to control, can fly with the loss of 1 engine and do emergency landing after loosing 2. It's available now in a kit for like $40k. Not too bad. I think it qualifies as an ultralight.

Not sure where I read it, following links in the article, that now they have proved the concept and shown basic useable stability w/o electronics, that the next step is to develop a computerized stability assistance of some sort. There are many improvements that would improve the stability to the machine even without electronics; one of the problems with relying too much on electronics for stability is how screwed you'd be when they fail.

It just doesn't work like that. Small tanks lose because of square-cube; for positive-pressure, the solution is just make it bigger, but for negative-pressure, big tanks have to be thick, else they fail by buckling.

What's wrong with hydrogen? Do you think you can build internal bracing lighter than it?

Gases occupy 22.4 liters of volume per mole of material at STP (standard temperature and pressure, which is 300 K, 1 atmosphere pressure). One mole of material weighs as many grams as the sum of the atomic numbers of the atoms in each molecule. Air is mostly Nitrogen, which is atomic number 7 and has an atomic weight of ~14. Since Nitrogen gas has two atoms per molecule, one mole (22.4 liters) of nitrogen weighs about 28 grams.

So if you take a 1000 liter (257 gallon) tank, and get it down to perfect vacu

All the articles I've seen they boast of this mechanical system for balancing the craft. The guy looks terrified to move even slightly. This type of VTOL craft is inherently unstable. There's a good reason he never guns it, the craft would flip. I'm sure it's perfectly capable of reaching a 100 to 200 feet or more but not safely. The LEM for the Moon landing was very similar but there was more finger crossing than technology involved in the first Moon landing. It's a cool idea but any moderately safe system would have to involve computers for balance correction rather then a mechanical linked system. They can become unstable in less than a second. Hearing it was mechanical in nature made me call bullshit before I even saw the video. After seeing it I'm still convinced that there's no passive way to make them safe. Even the Moeller Skycar with all it's computer assistance never got more than 15 feet off the ground. The Harrier jet was one of the few successful VTOL crafts that ever was ever widely accepted.

They are working on a very similar concept in Australia.http://www.hover-bike.com/index.html [hover-bike.com]I love the concept, but I agree. the stability problem needs to to be fixed with computers and gyros, not human balance. And when someone does finally nail it, it's going to be one hell of a toy!

Flywheel by definition adds weight, and either makes the vehicle difficult to turn or increases cost and complexity significantly. What is needed is a stationkeeping electronic control system. People trying to eliminate such are kidding only themselves. Only a goddamn ninja airman can fly an inherently non-aerodynamic aircraft which requires manual control.

Have you ever watched a pilot holding a helicopter in hover? That is a very non-aerodynamic, unstable aircraft with full manual control.

The inertia of the rotor gives it some inherent stability, and the move in helis is towards computer control, with the latest military models having the ability to hover in place if you let go of the stick as the front-mounted cannon tracks your view through the IR camera on the visor HUD.

A machine such as a hoverbike doesn't have to be stable, any more than a motorcycle has to be stable. The instability just has to have a natural period long enough to allow a person to react.

You would basically have the asshole-clenching experience of making a high-speed fly-by in a helicopter at very low altitude at all times except when you were trying to avoid one of the many obstacles near ground level tha

Mechanical gyro have pretty much been replaced by ring laser gyro [wikipedia.org] in everything except general aviation, you also need accelerometers [wikipedia.org] to do anything useful with the pilots seat out of the feedback loop.

"The LEM for the Moon landing was very similar but there was more finger crossing than technology involved in the first Moon landing. It's a cool idea but any moderately safe system would have to involve computers for balance correction"

If you put the fans ABOVE the center of gravity, such that the center of lift is above the center of gravity, then: a) it will look even more "bike" like, and b) you wont need to worry about negative stability.

The problem with all these powered lift gizmos (like the Williams X-jet and the Hiller VZ-1) is that you tend to fall out ouf the sky when your engine fails... The Hiller VZ-1 which is also a ducted fan used *two* 30 kW engines, but barely flew out of the ground effect [si.edu] and was limited in speed. More powerful versions had other control problems.

For autorotation you need long blades, negative pitch and enough altitude to work with. I cant see a ducted fan having much autorotation capability. They would lack the surface area and momentum necesary.

I get tired of pointing these guys out... but if you do your homework you will realize they are the real deal... and they are not rushing anything just to get some cheap PR. Eventually, I am confident they will succeed: